Six years later, she tells prospective donors what it takes: about $1,500 a year for each middle-school student beyond the nearly $12,000 in public funds the school receives per child.

She has relied on philanthropy, as well as loans and other sources of capital, to build D.C. Prep -- now with 740 students in one middle and two elementary schools -- to keep the program operating and, most importantly, to invest in her teachers.

Lawson uses the additional funding to hire more staff workers so the school can have longer days and so teachers have more time to prepare. She also pays teachers competitive salaries, subsidizes their cellphones and provides them with laptop computers.

"They become a better teacher during that time," Lawson said of the two hours a day in planning time. "It's like you invest in them and they are giving it back to the kids."

The middle school, in the 700 block of Edgewood Street, has become one of the highest-performing in the city.

"All the private schools are charging much more per pupil" than the city funding for each charter student, said Ibby Jeppson, director of resource development at D.C. Prep.

The money allows D.C. Prep to offer art and music, physical education, computer instruction and, at the middle school, enrichment programs so students can pursue their interests in depth.

Jeppson said D.C. Prep wants to give its students "the kind of opportunity to develop an extracurricular interest, like their affluent peers are doing over in Northwest."

Lawson, a Harvard University graduate with an MBA, grew up in the District and had dreamed of opening a charter to offer a good education to children from some of the city's toughest neighborhoods.

She searched for a space on a desolate block of empty warehouses, in the shadows of a crime-plagued public housing complex, and found a 37,000-square-foot building. "It was just one big, open space," she said. But "you could see the potential."

Lawson found more than $5 million in loans and $1 million in donations to buy and transform the warehouse into a middle school, which opened at that location in 2004. She said school leaders then saw the need to open an elementary school, because fourth-graders were arriving behind in reading and math.

In 2007, Lawson opened an elementary school in a renovated warehouse down the block. This year, D.C. Prep added another elementary school, in the former Benning Elementary School. Lawson plans to have 10 campuses in Northeast and Southeast.

For charter schools, there can be tension between growing and maintaining quality. As D.C. Prep expanded a year ago, the city's Public Charter School Board praised the program but warned that despite high scores, it had not met the requirements on its 2007 tests. Lawson said that D.C. Prep met the standards this year and that the board will reevaluate the program in 2009.

The cost of expanding has been substantial. The second building cost $12 million to buy and renovate, Lawson said. Fundraising is critical. "If you're going to buy a building, you have to raise money," she said.

D.C. Prep is one of about more than a dozen charter schools that have qualified for bond deals with the city by showing that they are financially sound and can attract students.

Lawson said she also had to learn how to raise money from donors. First, she went to her friends, then a bigger list of donors, working to build a core group of about 200 people and foundations she could approach each year. She had to develop a well-articulated mission and vision and come up with a basic figure for what she needed. "We wanted something to be able to say to our donors . . . 'This is about how much it is costing us every year to deliver a D.C. Prep education for every child,' " she said.

Donors are looking for educational innovation.

"What you find so often in education is that people know there is a problem, but they don't actually believe there is a solution. . . . Charters are a good way for us to learn what might be possible," said Marie Groark, a spokeswoman for the Bill and Melinda Gates Foundation, which supports the city's traditional public schools, D.C. Prep and other charters.

D.C. Prep eighth-grade math teacher Julie Moeller said the focus on personnel pays off. The weekly briefings and strategy sessions with her colleagues have been "a classroom for teachers," she said.

"That has improved my teaching. It's so directly tied to what I do in the classroom," she said. "Part of the reason I choose to stay here is there is a community of learners among the teaching staff."